Zirconium compounds as algaecides



United States Patent 3,446,656 ZIRCONIUM COMPOUNDS AS ALGAECIDES Charles J. Conner, New Orleans, La., assignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Dec. 30, 1964, Ser. No. 422,462 Int. Cl. D06m 11/12 US. Cl. 117138.5 1 Claim ABSTRACT OF THE DISCLOSURE Algecidal properties are imparted to cotton textiles by treatment with zirconyl acetate and zirconyl ammonium carbonate solutions which involves padding aqueous solutions containing 1.0 to 13.0% zirconia (ZrO to give wet pickup values of about 40% to 60%. Little or no fungicidal activity is imparted by the process of this invention. The algecidal activity has been observed to be of at least one year duration.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This application is related to copending application Ser. No. 422,461, filed December 30, 1964.

This invention relates to the preparation of zirconium compounds on cellulosics to impart to the said cellulosics algaecidal resistance. More specifically this invention relates to the impregnation of cellulosic textiles with aqueous solutions of zirconium compounds, which revert to insoluble derivatives of zirconia (ZrO when the treated textiles are dried and/ or heat cured. This invention finds utility in outdoor weathering where algae growths are a problem-algae growths are commonly found on canvas awnings, tarpaulins, boat covers, canvas sails, tents, etc.

The main object of this invention is to provide the cellulosic textile industries with an economical algaecidal treatment for cellulosic textiles wherein the treatment of the said cellulosic textiles consists of impregnating the cellulosic with low concentrations of certain zirconium salts.

A disclosure of this invention is the attainment of both fungicidal and algaecidal-as well as fungistatic and algaestatic-characteristics by a one-step process wherein the certain zirconium salts can be combined with other compounds which impart fungicidal and fungistatic characteristics to the cellulosic materials impregnated.

The prior art teaches that zirconium compounds are generally nontoxic and that these have never in themselves been referenced as algaecides. Zirconium compounds alone are poor fungicides relative to the zirconium metal content, but zirconium compounds have been reacted with copper and mercury compounds to produce zirconiumcopper and mercury derivatives of good fungicidal activity. Here the zirconium acts as a cellulosic locking on agent for the copper and mercury fungicidal component. Many copper and mercury fungicides-such as copper-8- quinolinolate, copper oxides, phenyl mercury salts, and the likea're not significantly algaecidal. It has been observed, also, that cotton textiles treated with the above fungicides have performed poorly in resisting algae growth but successfully in resisting fungi growth.

Now I have found that when a cellulosic material such as cotton fabric is wetted with an aqueous solution of either zirconium acetate or zirconyl ammonium carbonate and properly dried and cured, an insoluble zirconia dedrivative is produced which imparts to the treated fabric or other material a high degree of resistance to green algae growth. The exposure at weathering racks has been carried out for several years with no loss of resistance due to leaching. The untreated fabric submitted to parallel weathering becomes coated with green algae within a matter of months, and sometimes within a matter of weeks, depending on environmental conditions at time of exposure.

Since the staining and disagreeable appearance has been and still is a problem in the Gulf States of the United States, these zirconium compounds should gain in usefulness when applied by our methods, since these are applied to the cellulosic textiles from aqueous solutions, and are made insoluble by the application of heat, thereby rendering the textile algaestatic and algaecidal. It must be pointed out that the prevention of algae growth should be emphasized over the removal of the same growth, since algae will cause unsightly stains on fabrics even after the surface growth has been arrested.

A most attractive feature of this invention is the low cost of the treatment correlated with the high resistive activity to algae growth. Other features include nontoxicity to the processing personnel, low concentrations required, high stability to leaching, and application from aqueous solutions. The treated fabrics continue being algae resistant when submitted to leachings.

My discovery came about when I observed that the cotton duck and printcloth which I had treated with certain water soluble zirconium compounds and cured at certain temperatures, were not afifected by algae growth as were the untreated controls. The water soluble zirconium compounds when cured properly had formed water insoluble derivatives. It was observed that these insoluble derivatives when locked onto cotton would impart a1- gaecidal properties to cotton. More specifically, it was noted that fabrics which had been treated with various concentrations of zirconyl acetate in aqueous solutions to yield final add-ons of zirconia (ZrO of from about 0.5% to 13.0% in the form of the dried basic acetate of zirconium, were all practically 100% free of the green algae growth which completely covered the control untreated duck as well as the printcloth which was also used in these tests.

At a later date further observations were made wherein we noted that cotton treated with zirconyl ammonium carbonate in varying concentrations decomposed on cotton on oven-curing and again the zirconium substance deposited on the cotton did also impart to it algaecidal properties. Upon analysis we learned that zirconia had been formed.

It should be obvious to those skilled in the art that projections can be predicted to include homologues of the two compounds which gave us the unexpected results. It is felt that if zirconium propionate, butyrate, and the like would be employed the results would be the same.

Considering the case of zirconyl acetate in aqueous solution, decomposition of the acetate occurs when the solvent has been driven off and the temperature is higher than about C. The reaction products are basic water insoluble zirconyl acetate and acetic acid. The basic insoluble zirconyl acetate is a derivative of one mole of zirconia and one mole of acetic acid. The decomposition may be represented by the following equation.

The decomposition of zirconyl ammonium carbonate may be represented by the following equation.

The hydrated zirconia (zirconium hydroxide) so produced is an excellent algaecide when deposited on cotton. The hydrated zirconia can also be represented as a molecule of zirconia with two waters of hydration; thusly, ZrO -ZH O.

The application of these compounds to cellulosic textiles is generally carried out by conventional methods, and fortunately these substances which are used as illustrations in the examples can be applied from aqueous solutions. The ZrO content of the solutions for impregnating the cellulosic materials ranges about from 1.0% to 13.0% in ZrO content. The drying and/or ouring is again conventional, and the temperature applicable range is about from 80 to 160 C.

The preferred standard for impregnating cotton in order to produce a suitable and economical final product can be described in this manner. I prepare the zirconium salt in aqueous solutions about from 1.0% to 6.5% Zr content. These solutions are then padded onto the fabric or other textile to obtain about from 40% to 60% wet pickup. The material is then dried, then cured, to drive off the water solvent and other decomposition products, and to leave an insoluble zirconia derivative in the textile. Although the drying and curing can be performed in a continuous manner, in order to prevent migration of the treatment I prefer a 2-step process where I dry the impregnated material first at temperatures about from 80 to 100 C., then this is followed with heat curing of the dried fabric at temperatures ranging about from 100 to 160 C. to drive off the byproducts produced in the reaction.

More specifically, I prefer to dry the impregnated material about from 3 to 5 minutes at 80 C. A 3-minute drying at 80, followed by a 2-minute cure at about 145 C. has been satisfactory in many of our experiments.

Example 1 A 6.5 ZrO zirconyl acetate solution, which was prepared from a 13% Zr0 zirconyl acetate solution (containing 12% free acetic acid) and water, was padded onto bleached and scoured 8-oz. cotton duck. The wet fabric was submitted to a drying and curing heat treatment of 5 minutes at 145 C. in an oven. The finished fabric was exposed to outdoor weathering, together with the appropriate untreated control, for exactly 12 months.

When the test samples were removed for analysis it was noted that the treated sample showed no growth on either side, while the untreated sample had been showing considerable growth of green algae since about the third month of exposure.

Example 2 A 5.0% Zr0 zirconyl ammonium carbonate solution, which was prepared from a Zr0 zirconyl ammonium carbonate solution and water, was padded onto bleached and scoured 8-oz. cotton duck. The wet fabric was submitted to a drying and curing heat treatment of 5 minutes at 145 C. in an oven. The finished fabric was 4 exposed to outdoor weathering, together with the appropriate untreated control, for exactly 12 months.

When the test samples were removed for analysis it was noted that the treated sample showed no growth on either side, while the untreated sample had been showing considerable growth of green algae since about the third month of exposure.

Example 3 Ten aqueous solutions of zirconyl acetate containing, specifically, concentrations of 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, and 9.0% ZrO were prepared according to the procedures in Example 1. Each of these solutions was impregnated onto each of 11 duck samples of dimensions suitable for outdoor weathering. The 11 samples, together with an untreated duck sample, were exposed to outdoor weathering for a period of exactly 12 months, at which time all were removed for evaluation.

It was noted that while the untreated duck sample was covered with the green algae on the underside, none of the treated samples showed a trace of the same green algae growth.

Example 4 Five aqueous solutions of zirconyl ammonium carbonate containing, specifically, concentrations of 1.5%, 1.0%, 2.5%, 5.0%, and 7.0% ZrO were prepared according to the procedures of Example 1. Each of these solutions was impregnated onto each of five duck samples of dimensions suitable for outdoor weathering. The five samples, together with an untreated duck sample, were exposed to outdoor weathering for a period of exactly 12 months, at which time all were removed for evaluation.

It was noted that while the untreated duck sample was covered with the green algae on the underside, none of the treated samples showed even a trace of the same green algae growth.

I claim:

1. A method for rendering cellulosic material resist-ant to algae growth, comprising:

(a) wetting the cellulosic material with a solution consisting of water having dissolved therein zirconyl ammonium carbonate wherein the Zr0 content of the solution is about from 1.0% to 13.0%,

(b) drying the impregnated wet cellulosic material at temperatures about from to for periods about from 3 to 5 minutes, and

(c) curing the impregnated dry cellulosic material at temperatures about from 80 to C. for periods about from 1 to 3 minutes to convert the zirconium ammonium carbonate to hydra-ted zirconia as a deposit thereon.

1,717,483 6/1929 White 117-169 X 1,745,134 1/1930 White et al. 167-38.6 2,361,830 10/ 1944 Edelstein 117-169 2,482,816 9/1949' Van Mater 117-143 X OTHER REFERENCES Blumenthal, W. B., Rayon and Synthetic Textiles, 81, 82, and 83 (December 1950).

WILLIAM D. MARTIN, Primary Examiner. H. J. GWINNELL, Assistant Examiner.

US. Cl. X.R. 

